The argument, there is no box, makes more sense to me in terms of the actual episode. I was just thinking of Alex's talk with Locke, and how everybody thinks they are following their own ideas when it's really Ben's ideas. Maybe that is all ben can do now, manipulate people to cause the things to manifest, i.e. cooper. If there was a "box" Ben wouldn't of needed to goad Locke like he did, he simply could have wished cooper was there on the island, or get one of his lackeys to do it. For some reason I don't think the "island/box/whatever" is working for Ben anymore, otherwise he would be healthy.